English: Example of k-NN classification. The test sample (green dot) should be classified either to the first class of blue dots or to the second class of red dots. If k = 3 (black line circle) it is assigned to the second class because there are 2 red dots and only 1 blue dots inside the inner circle. If k = 5 (orange line circle) it is assigned to the first class (3 blue dots vs. 2 red dots inside the outer circle).